Typically, when a processing device is turned on, a boot sequence is initiated to load an operating system and/or a software application into the main memory (e.g., random access memory (RAM)) for the device. The processing device hardware generally uses a small piece of software code that serves to load the operating system. Once loaded, the operating system can be used to control operations performed by the device.
The boot sequence involves using a boot loader to locate code that is used to actually load the operating system. In a typical computer, the boot loader or the basic input-output system (BIOS) is stored in a read only memory (ROM) or in a NOR flash memory at a specific address and serves as a pointer to other locations where the boot code or other application code is located. Similarly, in a typical handheld device, such as an MP3 player or personal digital assistant (PDA), the boot loader is stored in ROM or in a NOR flash memory.